Why Turf Grass Needs to Be Fertilized

Avoid spreading too much nitrogen on grass or it can cause burning.

Turf grass uses up nutrients in the soil more quickly than can be naturally replenished. Without adequate amounts of nutrients, lawns become bare and unhealthy. So fertilizers are used to provide missing nutrients and keep turf grass healthy. There are three primary nutrients that lawns need: nitrogen, phosphorous and potassium.

Nitrogen

Nitrogen is the most important nutrient for growing grass. Vegetation cannot make the proteins it needs to grow without nitrogen, which also helps grass complete photosynthesis, spread across the lawn and maintain strong blades. Soil that lacks nitrogen results in leaf discoloration and stunted growth. Fertilizers high in nitrogen generally are used in the beginning of the growing season, throughout the growing season and near its end, before the grass goes dormant. Using nitrogen while grass is dormant can cause new growth that becomes damaged during winter.

Phosphorous

Phosphorous helps grass transform sunlight into usable energy and aids in root growth. If your soil's pH range is lower than 6.0, phosphorous is not available to the grass. It is important to check your soil's pH range every year to ensure that phosphorous is present. Because phosphorous is so important, it has the highest percentage in starter fertilizers used during seeding, according to the University of California Division of Agriculture and Natural Resources.

Potassium

Potassium is the second most-used nutrient for plants after nitrogen. This primary nutrient helps plants fend off fungal diseases, photosynthesize and build protein.You may see grass begin to discolor when potassium is lacking in the soil. Soil must be moist in order for grass to be able to use potassium. In addition, potassium is at its most available when soil temperature is between 60 to 80 degrees Fahrenheit, according to University of Minnesota Extension.

Other Nutrients

Other nutrients in fertilizer include calcium, magnesium and sulfur. Calcium is needed by grass cell structure. Magnesium is a major component in chlorophyll, which helps keep plants green. Grass must have sulfur to produce protein, form chlorophyll, resist winter damage and develop vitamins. Generally, sulfur is added to low-grade fertilizers. The best way to know which nutrients are lacking in your yard is to conduct a yearly soil test. You can send a soil sample to your local cooperative extension office to have a soil analysis performed.

References

• University of Minnesota Extension: Potassium for Crop Production; George Rehm and Michael Schmitt, 2002
• North Carolina Department of Agriculture and Consumer Services: Plant Nutrients
• University of California Statewide Integrated Pest Management: Site Preparation